[Scons-dev] howto debug configure

[Paweł Tomulik]

William,

Neal is the original author of this thread. I just replied with a 
possible solution. The PR report I mentioned contains an example. Let me 
just paste it here:

<code>

# SConstruct
#
# The CheckHello should return 'yes' if everything works fine. Othervise it
# returns 'failed'.
#
def hello(target, source, env):
   import traceback
   try:
     print 'hello!\n' # this breaks the script
     with open(env.subst('$TARGET', target = target),'w') as f:
       f.write('yes')
   except:
     # write to file, as stdout/stderr is broken
     traceback.print_exc(file=open('traceback','w'))
   return 0

def CheckHello(context):
   import sys
   context.Display('Checking whether hello works... ')
   stat,out = context.TryAction(hello,'','.in')
   if stat and out:
     context.Result(out)
   else:
     context.Result('failed')
   return out

env = Environment()
cfg = Configure(env)

cfg.AddTest('CheckHello', CheckHello)
cfg.CheckHello()

env = cfg.Finish()

</code>

Few words of explanation:

The above code raises "TypeError: unicode argument expected, got 'str'" 
in the line "print ....". Normally such an exception is eaten by SConf 
machinery and it's quite hard to debug. Above I just write its backtrace 
to 'traceback' file, as stdout/stderr is captured by SConf.Streamer 
which is broken. The backtrace points to line 183 of SCons/SConf.py:

Traceback (most recent call last):
   File "SConstruct", line 9, in hello
     print 'hello!\n' # this breaks the script
   File "/usr/lib/scons/SCons/SConf.py", line 183, in write
     self.s.write(str)


Here the "self.s" object is an instance of io.StringIO. On python 2.x 
io.StringIO accepts only unicode, and doesn't accept str - and this is 
main reason why this code fails.

W dniu 03.04.2014 19:40, William Deegan pisze:

> Pawel,

 >
 > Likely you’re better off bringing such questions to the users mailing
 > list. The devel mailing list is meant to discuss the internal
 > development of SCons. I’m cc’ing that list. I believe there is a
 > config.log generated when you run the configure context.
 >
 > Also, can you create a small reproducible test case for this? That
 > way we can try it out and see what’s going on.
 >
 >
 > -Bill
 >
 > On April 3, 2014 at 2:13:01 AM, Paweł Tomulik
 > (ptomulik at meil.pw.edu.pl) wrote:
 >> W dniu 06.09.2013 19:47, Neal Becker pisze:
 >>> I have a lot working, but not configure. I don't know how to
 >>> debug it.
 >>>
 >>> even with --debug=stacktrace, the stack trace is not useful. I
 >>> don't have any idea where this error is coming from:
 >>>
 >>> file ,line 92: Configure(confdir = .sconf_temp) scons: Configure:
 >>> Checking for C header file unuran.h... .sconf_temp/conftest_0.c
 >>> <- | |#include "unuran.h" | | scons: Configure: Caught exception
 >>> while building ".sconf_temp/conftest_0.c":
 >>>
 >>> Traceback (most recent call last): File
 >>> "/home/nbecker/scons-replaced-by-scons-
 >>> p3/bootstrap/src/engine/SCons/Job.py", line 201, in start
 >>> task.execute() File "/home/nbecker/scons-replaced-by-scons-
 >>> p3/bootstrap/src/engine/SCons/SConf.py", line 352, in execute
 >>> raise e TypeError: unicode argument expected, got 'str'
 >>>
 >>> _______________________________________________ Scons-dev mailing
 >>> list Scons-dev at scons.org
 >>> http://two.pairlist.net/mailman/listinfo/scons-dev
 >>
 >> Hi,
 >>
 >> I think, this is a bug in SCons. I've addressed it in BitBucket PR
 >> 126: https://bitbucket.org/scons/scons/pull-request/126/
 >>
 >> Best Regards!
 >>
 >> -- Pawel Tomulik
 >>
 >> _______________________________________________ Scons-dev mailing
 >> list Scons-dev at scons.org
 >> http://two.pairlist.net/mailman/listinfo/scons-dev
 >>
 >


-- 
Pawel Tomulik

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